Histological features of serous tubal intraepithelial lesion (STIL).

<p>Two representative STILs (right and left) are shown. STIL on the right is a linear expansion of p53-positive tubal epithelial cells that show no morphological atypia, but increased Ki-67 labelling index (≥10%). STIL on the left consists of p53-positive tubal cells with mild to moderate morphological atypia. It is suspicious for serous tubal intraepithelial carcinoma on morphological basis. However, its Ki-67 labelling index is low (< 10%).